GE 7-2875A AM/FM Radio “Baby SR”

And a look at the completely different GE 7-2857A

The GE 7-2875A is one of a few mid-sized GE portables unofficially referred to by hobbyists as “Baby SR’s…smaller relatives to the very popular original GE Superadios. They were sold in the late 70’s and 80’s concurrently with the Superadios and although they are quite different internally than the SR’s and don’t actually perform quite as well, they are nevertheless very nice analog portable radios with good performance and many positive attributes. GE offered a huge range of radios many of which were good performers and there were a several worthy of the name “Baby SR” including models 7-2850 and 7-2881 to name a few. This report focusses on the GE 7-2875A which is one of the nicer models, and we’ll also look at the confusingly similarly named model 7-2857A…just two transposed digits but a completely different radio. GE nicknamed the 7-2875A “The Performer” and advertised its “Big Sound”. It is an all-analog design and as such features smooth, natural tuning and low current drain. I found a nice sample in the original box which was working well and did not need any repairs although I did go through the alignment as I usually do to be sure performance was maximized…as with most of the SRs I have seen over the years I found that it was quite close as received. (BTW I have never been able to find a Service Manual for this radio so if anyone can provide me with one I would be grateful. And speaking of confusing model numbers, I bought a SAM’s Photofact for the radio from SAM’s Technical Publishing (https://www.samswebsite.com/) – a resource I have used often over the years but what I received was for the lesser model…they quickly refunded my money and found they had no manual for the 7-2875A).

Baby Flanked By SR & SR II

I want to be clear that none of these Baby SR’s match the overall performance of the real Superadios and I wouldn’t expect them to because although these are good performers in their category there are some cost-cutting measures in their design which keeps them a notch below the Superadios. Let’s get into some details of the 7-2875A’s design. The smaller 7-2857A is a nice, smaller radio which is just a tad below the larger model’s performance as we shall see.

Physical Design: The 7-2875A features a heavy, solid feel and measures 11.4 x 7.1 x 3.5 inches size and has a quality feel. It features a large slide rule dial with precise vernier tuning, separate bass and treble controls, a 5” speaker, mono earphone jack, switchable AFC and a quiet, built-in AC power supply. Being all analog, it will give long battery life on its 6 C cells.

The first order of business was to compare the design of the 7-2875A with the actual Superadio and Superadio II to see what differences there are. Apart from the smaller size (see pictures) one big difference is the internal ferrite rod AM antenna which measures 7 7/8” on the Superadios and 4” in the 7-2875A. While this does not cut AM sensitivity in half as you might think, it is certainly a compromise. I also noted that whereas the Superadio and Superadio II have Tuned RF stages on AM with three gang air variable tuning caps, the “baby” has the much more common two-gang ceramic vari-cap which is another small compromise. There is also a less complex IF chain in the baby. But overall design is good – old-school all the way with mostly discreet components and solid mechanical parts. There is one IC which GE promotes right on the front of the radio, a T900 BI-K which consolidates and simplifies some of the RF/IF and AF (audio) portions of the circuit and was used in many GE models of the period. The SR’s also used an IC for many of the same functions.

The Rubber Hit’s The Road: OK, so the 7-2875A is quite different from GE’s Superadios, but how well does it compare side by side with its big brothers on AM? In two words – surprisingly well. I spent several days and evenings with the radio side by side with an original SR and an SR II as well as other reference radios and after tabulating pages of loggings found that the 7-2875A was quite sensitive and selective, but the differences were very real with weaker signals when circumstances allowed them to be revealed. To explain, on many signals the 7-2875A seemed quite similar to a Superadio with little difference in perceived reception. But when signal levels dropped down nearer the threshold of readability the Superadios were able to make them louder and clearer while they were weaker sounding on the 7-2875A. This is likely directly attributable to the difference in the size of the ferrite rod antenna, the lack of that tuned RF stage and fewer IF stages than in the SR’s…the larger ferrite rod and that extra amplification make the difference when signals are very weak, helping to bring them up in level. There were also a few situations where the tuned RF stage allowed the SR’s to hear signals which were desensitized on the baby due to the presence of stronger signals around them…again, a hallmark of a tuned rf stage and more sophisticated IF design, although this was a subtle difference in most cases. For perspective I have to repeat what I always say – unless your local noise/RFI is fairly low these two radios are close enough that you may be hard-pressed to hear the differences because a higher noise floor will mask the differences. Indeed, when I tested the radios in a slightly higher noise environment the difference disappeared.

On FM the two radios were more similar with each performing like the typical FM portables of their day…sensitive but not as selective as today’s radios. The GE 7-2875A ranks *** on both AM and FM Mega Shootouts. Note: *** is more impressive on AM and is as good as most current production AM/FM/SW radios. The smaller 7-2857A was very close in reception and showed very good performance. The smaller radio lacks a swivel on the FM whip antenna which limits its adjustability for signals which might benefit from it…that seems like a poor decision on GE’s part. Also the smaller radio lacks an AFC defeat switch…another compromise.

One big difference is service access. The larger radio is easy to work on because it is easy to disassemble while keeping the main parts interconnected and working, but the smaller radio would seemingly require undoing the dial string to access the board…my sample seemed to be working very well so I left well enough alone.

Left: 7-2875A – Right: 7-2857A

Sound Quality is very good on the 7-2875A – not quite as full and rich as an SR but better than many same-sized portables and its bass and treble controls make it easy to adjust to your liking. The SR’s had a wider frequency response, especially the SR II with its separate tweeter which provided a clearer and more defined treble range on FM to sounds like cymbals and strings but the baby was not far behind with great sound in this category. The smaller 7-2857A has a single tone control and a somewhat mellower sound quality, but it’s hard to fault for the size and price…overall I think most people would find it pleasant to listen to.

Conclusion: The GE-7-2875A is worthy of the name “Baby Superadio”. It comes fairly close to SR performance in many areas and is overall a sturdy and fun radio with a very nice feel…it is a great all-analog radio and I like its large, clearly marked tuning dial. It is almost a shame to put it in the shadow of the Superadios because among other mid-sized all-analog portables it is a top performer, and if you love old analog radios with good AM performance, I think you will like this one. The smaller 7-2857A is a small notch below it overall in reception and sound but again, it’s a wonderful old analog radio and you could have lots of fun tuning around with one, but given the choice I’d choose the 7-2875A. After all, everyone loves a baby!

Recommended!

Jay Allen

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